Using HP Serviceguard for Linux with Red Hat KVM Guests, May 2013

Technical white paper | Using HP Serviceguard for Linux with Red Hat KVM Guests

Supported cluster configuration with KVM guests

The supported HP Serviceguard for Linux cluster configuration when using KVM guests as cluster nodes are as follows:

Cluster with KVM guests from a single host as cluster nodes

In this configuration a cluster is formed with KVM guests all of which are carved out of a single host (cluster in a Box).

Though this configuration provides consolidation of resources this is not ideal. A failure of the host will bring down all the

nodes of the cluster which is a single point of failure. Hence this configuration is not recommended.

Figure 1. Cluster in a Box

Cluster with KVM guests from multiple hosts as cluster nodes

In this configuration a cluster can be formed with KVM guests that are carved out of two or more hosts. Serviceguard is

installed on the KVM guests and a cluster is formed with these VMs. Serviceguard provides high availably to only the

applications running as packages in the VMs and fails over the application in case of failures. Multiple VMs from single host

can be configured in the same cluster as nodes; however, please note that the failure of any one of the hosts should not

result in more than half the cluster nodes going down. Hence we need to ensure that the cluster nodes are equitably

distributed across the hosts.

Let us consider a four-node cluster. In this case the correct distribution would be to have two VMs each on two hosts

configured as Serviceguard cluster nodes, rather than having three VMs from one host and one from the other. In the

second case the failure of the host with three VM as nodes will bring down the entire cluster.

Figure 2. Cluster with KVM guest nodes across multiple hosts